From: Andy Soos, ENN
Published May 23, 2013 04:08 PM

New Anti-Staph Drugs

Bugs and infections are growing ever stronger and more resistant to the antibiotics and the like. A team of Wisconsin scientists has synthesized a potent new class of compounds capable of curbing the bacteria that cause staph infections. They describe these new agents as effectively interfering with the quorum sensing behavior of Staphylococcus aureus, a bacterium at the root of a host of human infections ranging from acne to life-threatening conditions such as pneumonia, toxic shock syndrome and sepsis.

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"It's a whole new world for us," says Blackwell, whose group identified peptide-based signaling molecules that effectively outcompete the native molecules the bacterium uses to communicate and activate the genes that cause disease.

Quorum sensing is a system of stimulus and response correlated to population density. Many species of bacteria use quorum sensing to coordinate gene expression according to the density of their local population. In similar fashion, some social insects use quorum sensing to determine where to nest. In addition to its function in biological systems, quorum sensing has several useful applications for computing and robotics.

Quorum sensing can function as a decision-making process in any decentralized system, as long as individual components have: (a) a means of assessing the number of other components they interact with and (b) a standard response once a threshold number of components is detected.

Bacteria use quorum sensing to assess their population density and coordinate certain behaviors. They do so through the use of pheromone-like chemicals, which bind to receptors either in the bacterial cell or on its surface and tell it if there are enough companion bacteria around to switch on genes that perform certain functions. In the case of Staphylococcus aureus, quorum sensing activates toxin production, manifesting disease in the host.

Interfering with bacterial quorum sensing to stymie disease is considered a promising new antibiotic strategy, says Blackwell. Staph, she adds, is an excellent target as the bacterium is not only a prevalent pathogen, but some strains, notably methicillin-resistant Staphylococcus aureus or MRSA, have developed resistance to commonly used antibiotics such as penicillin and its derivatives.

Staphylococcus is a group of bacteria that can cause a number of diseases as a result of infection of various tissues of the body. Staphylococcus is more familiarly known as Staph. Staph-related illness can range from mild and requiring no treatment to severe and potentially fatal.

The new compounds synthesized by Blackwell and her colleagues are peptides that work at very low concentrations by blocking the chemical receptors the bacterium uses to regulate quorum sensing. The new agents devised by Blackwell and her group work on the four subtypes of staph, all of which use different quorum sensing signals and are found in different infection types.

For now, the compounds devised by the Wisconsin team will have their greatest impact in the lab as research probes to further study the role of quorum sensing in Staphylococcus aureus. 

For further information see New Staph Drug.

Staph image via Wikipedia.

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